Air Quality in the Home: Common Pollutants and Sources

The average American spends 90% of their time indoors! The quality of the air we breathe inside our home matters greatly to our health. You may be encountering a wide range of pollutants, which may be mildly or seriously affecting your health. The good news is that there is plenty that you can do to improve your indoor air quality and reduce your exposure to harmful pollutants. The first step is learning what those pollutants might be. The following article contains information that will soon be available as a fact sheet, available for free at the Ecology Center or on our website.

Air pollutants fall into three general categories: particulates, gases, and radon.


The first type is the tiny particles from woodstoves and unvented combustion appliances such as gas stoves that can penetrate deep into the lungs and stay for a long time, causing acute or chronic effects. The second type is the larger particles such as mold, pollen, dander, and house dust, which doesn’t penetrate as deeply but may cause an allergic response. The health effects of particulates depend on the types and concentrations of particles present, the frequency and duration of exposure, and an individual’s sensitivity.

Gaseous Pollutants

  • Carbon Monoxide (CO) is a colorless, odorless gas that is a byproduct of incomplete fossil fuel combustion. CO interferes with the delivery of oxygen in the body. It can cause headaches, dizziness, weakness, nausea, confusion, fatigue, increased chest pain in people with chronic heart disease, and death. California now requires that residences with fossil fuel sources or attached garages have CO detectors and fire and smoke detectors installed.
  • Nitrogen Dioxide is also a byproduct of fossil fuel combustion and is a smelly, reddish brown gas that irritates the mucous membranes in the eye, nose, and throat and can cause shortness of breath. There is evidence that high concentrations or continuous exposure to nitrogen dioxide increases the risk of respiratory infection. Animal studies suggest that repeated exposures to elevated nitrogen dioxide levels may contribute to the development of lung disease such as emphysema. Children and individuals with asthma and other respiratory diseases are at particular risk.[1]
  • Volatile Organic Compounds (VOCs) are a certain class of carbon-containing compounds that evaporate easily. Formaldehyde, benzene, toluene, and styrene are well-known VOCs. A related group of chemicals are called semi-volatile organic compounds (SVOCs), and include phthalates, halogenated fire retardants, perfluorocarbons, and some pesticides. Effects of exposure to VOCs include eye, nose, and throat irritation; headaches, loss of coordination, nausea; and damage to liver, kidney, and central nervous system. Some VOCs are suspected or known to cause cancer in humans.

Radon [2]

The most common source of indoor radon is uranium in the soil or rock on which homes are built. As uranium naturally breaks down, it releases radon gas, which is colorless, odorless, and radioactive. Although it’s not common in the East Bay, radon is one of the most serious indoor air hazards in the US and Europe.[3] Exposure to high radon levels is associated with lung cancer. Scientific evidence indicates that smoking combined with radon is an especially serious cancer risk. A low-cost test can be performed to determine radon levels, and simple solutions implemented to fix the problem.[4] The EPA’s Consumer’s Guide to Radon Reduction is the place to start.

Sources of Indoor Air Pollution

SMOKE: Candles, Incense, Woodsmoke, Cigarettes

Most candles on the market today are made with paraffin, a derivative of petroleum. When burned, paraffin candles release known carcinogens (cancer-causing substances) such as benzene, toluene, formaldehyde, acetaldehyde, and acrolein. Plus, they release soot into the air, which can cause asthma and other respiratory problems. Most incense combines plant resins, wood powders, perfumes, and oils with glue that contains formaldehyde and phthalates. When burned, carcinogenic polycyclic aromatic hydrocarbons are released into the air, along with various gases like CO, sulfur dioxide, and nitrogen dioxide.[5] Woodsmoke and cigarettes release a similar stew. Burning incense produces VOCs benzene, toluene, and xylene, which cause respiratory irritation and can even trigger DNA mutations. Gasses and particulate matter permeate rapidly through indoor spaces and can leave toxic residue.[6]

Solutions: Beeswax and soy candles do not generally produce soot or toxins when burned. To clear the air, open windows and doors. As an incense alternative, try a drop of essential oil in a bowl set on a radiator or in an aromatherapy candleholder. Please note that some people may be sensitive to essential oil and “natural” scents as well. Briefly simmer apple cider with spices, or simmer combinations of mint, citrus peel, rosemary, bay leaves, and cloves. Better Basics for the Home by Annie Berthold-Bond contains many useful recipes for scenting your space.

APPLIANCES: Gas Stoves, Furnaces, Driers, or Space Heaters

Unvented appliances that run on natural gas or kerosene can release carbon monoxide, particulates, and nitrogen dioxide. To avoid these dangers, use an exhaust fan over gas stoves and ranges that vents to the outdoors, and keep the burners properly adjusted. A persistent yellow-tipped flame indicates maladjustment. All furnaces, flues, and chimneys should be inspected and repaired annually. When using a fuel space heater, follow manufacturer instructions carefully and ventilate the room.[7] Clean the filter on forced air furnaces frequently.

BUILDING MATERIALS: Furniture, Particleboard, Cabinetry

Formaldehyde can enter the air from furniture, building materials, particleboard, and cabinetry in your home. In 2011, after years of delay because of intense lobbying from the chemical industry,[8] the federal government finally listed formaldehyde as a carcinogen. Since 1992, formaldehyde has been formally listed as a Toxic Air Contaminant with no safe level of exposure by the California Air Resources Board. Formaldehyde may cause burning sensations in the eyes and throat, nausea, and difficult breathing. High concentrations may trigger asthma attacks. When possible, choose reused furniture; the VOCs are likely to have already off-gassed (i.e. evaporated into the air). Pick solid, sustainably harvested wood or metals rather than particleboard.


Common pesticides and disinfectants used indoors contain a variety of chemical compounds that can irritate your eyes, nose, and throat, and cause headache, dizziness, muscular weakness, and nausea. Exposure can be linked to increased risk of cancer, and chronic exposure to some pesticides can damage the liver, kidneys, endocrine and nervous systems.[9] Integrated Pest Management (IPM) strategies exist that eliminate or reduce the need for chemical pest control. Hydrogen Peroxide, borax, vinegar, and alcohol have been proven to be effective disinfectants.


New carpet and vinyl flooring can off-gas VOCs. Carpet can also hold particulates and VOCs that cause respiratory problems. For more detail on carpet, refer to this Ask the EcoTeam column.[10] Synthetic carpets are made from nylon fibers with a polypropylene backing. Of the chemicals released from carpet, most notable are styrene and 4-phenylcyclohexane (4-PC), both of which come from the latex backing used on 95 percent of carpets. The “new carpet” aroma is the odor of 4-PC off-gassing, which is an eye– and respiratory-tract irritant that may also affect the central nervous system. The adhesive used to affix the carpet to the floor typically contains benzene and toluene.[11] Solution: Even the best wall-to-wall carpet is a haven for dust mites, mold spores, and lingering VOCs, and is usually one of the largest hosts of contaminants in our homes. Avoid wall-to-wall carpet whenever possible. Choose area rugs on a bare floor that can be cleaned to remove pollutants that collect in them. Choose natural linoleum rather than vinyl flooring.


Perchloroethylene (PERC), the chemical most widely used in dry cleaning, accumulates in body fat. Studies have shown that women exposed to this chemical have an increased risk for breast cancer. Short-term exposure may cause skin irritation, dizziness and headaches. Low levels of this chemical off-gas from dry cleaned clothes. The EcoDirectory lists cleaners who use alternative methods to dry cleaning. New drapes and linens may have been treated with formaldehyde. Wash them before using or unwrap and let new items air outside for a week before bringing them in. Shower curtains made from vinyl (PVC) emits scores of VOCs and phthalates. Shower curtains made from cotton, hemp, or the plastic EVA are available as alternatives.


Cleaning products sometimes contain chemical ingredients listed as asthmagens, carcinogens, reproductive toxins, or toxic air contaminants.  Ingredients of concern that have been frequently identified in cleaning products include quaternary ammonium chlorides or “quats,” glycols and glycol ethers such as 2-butoxyethanol, ethanolamine, some alcohols such as benzyl alcohol, ammonia, and chlorinated hydrocarbons. The volatile components of these chemicals are emitted into indoor air during and after the cleaning processes and may adversely affect indoor air quality. For safer alternatives, refer to the Ecology Center’s Alternative Cleaning Recipes fact sheet in both English and Spanish.

Fragrance is added to many cleaners, laundry detergents, and fabric softeners. The chemical formulas of fragrances are considered trade secrets, so companies aren’t required to list their ingredients on product labels, even though many contain VOCs linked to asthma, allergies, headaches, and cancer. VOCs and SVOCs are released from many deodorants, hair sprays, shampoos, toners, nail polishes, perfumes, and air fresheners. To avoid these hazardous chemicals, select fragrance-free products and avoid aerosols. Wear essential oils in lieu of perfumes or no scents at all if in contact with people that are environmentally sensitive.


Biological contaminants include molds, mildew, animal dander, cat saliva, house dust mites, cockroaches, and pollen. All can trigger allergies or asthma. To control exposure to these contaminants, clean and vacuum regularly, preferably with a HEPA filter. Wash bedding in hot water. Mold, mildew, and roaches thrive in humid conditions; control the humidity in your house using bath and kitchen exhaust fans. Refer to the California Health Department for more guidance on mold.


Spend more time in the great outdoors! From time to time, open your windows and doors and let fresh air circulate. Decorate your house with houseplants that filter the air. NASA has compiled a list of plants that eliminate significant amounts of benzene formaldehyde, and trichloroethylene from indoor air.

Sources / Resources







[7] For much more information see



[10] From Ask the EcoTeam


[Photo by Diego Torres Silvestre]

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7 thoughts on “Air Quality in the Home: Common Pollutants and Sources

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  2. Very interesting and useful blog. Thanks for sharing.I too want to share my point of view regarding radon. Radon is a very harmful and dangerous gas. It destroys health of a normal human being. It is therefore recommended to test your home for radon gas and get removed immediately.

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